While the Portuguese may have attempted to rebrand himself as "The Happy One" on his return to English football, he was anything but at St. James' Park.

Prior to his team's home game against their Champions League Group E rivals Schalke, his programme notes made it clear that he felt the responsibility for Chelsea's loss fell at the feet of his players and their questionable commitment to the cause.

Mourinho in #cfc#schalke prog: "At Newcastle we had no ambition in our game. Tonight we have to make sure our attitude & ambition are back'

With Fernando Torres out due to a leg injury, and their manager set to ring the changes after his dissatisfaction at the performance in the North East, Chelsea's starting 11 will have much to prove.

Thankfully Mourinho's team fared much better in their last game in Europe, beating Schalke away 3-0 at the Veltins-Arena in Gelsenkirchen a fortnight ago.

Due to that loss at home the Bundesliga outfit arrive in London needing to secure at least a point to keep pace with Basel, who are likely to beat Steaua Bucuresti in Group E's other fixture on Match Day 4.

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The Royal Blues have been decent-to-good so far this season and sit in sixth place, 12 points off leaders Bayern Munich but within the Europa League places.

Existing injuries to key players such as Klaas-Jan Huntelaar, Jefferson Farfan and Marco Hoger mean that Schalke's other stars and reserve players must make the step up to ensure the club are competitive at home and abroad heading into Christmas.

Below are the six players who must produce big performances in Chelsea and Schalke's Champions League clash at Stamford Bridge.

Andre Schurrle

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Signed from Bayer Leverkusen in the summer for around £18m, like many of the other players at his new club Andre Schurrle is yet to truly set the Premier League or Champions League alight in a Chelsea shirt.

The German did perform well in his team's 4-0 win over Bucheresti early in the group stage and opened the scoring in the 2-1 victory against Manchester City, but with Mourinho lamenting the team's lack of inspiration against Newcastle, Schurrle has a big opportunity to impress against Schalke.

Juan Mata may well be one of the players to suffer from Chelsea's loss to Newcastle with Mourinho having already benched the Spaniard earlier in the year due to concerns over his mentality and work rate.

Juan Mata: Only Franck Ribéry (3.75) has averaged more key passes per game than @juanmata10 in the CL this season (3.5) #UCL#CFC

However, Mata remains one of the Blues' very best players, and Schurrle must dig deep to eclipse the former Valencia winger by illustrating the qualities that made him one of the Bundesliga's most devastating support strikers last season.

Schalke certainly won't have forgotten about him. So, the forward must be at his best to beat a team far more aware of the threat he poses than the English defences he has faced more recently.

Kevin-Prince Boateng

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Ejected by AC Milan to make space for the prodigal return of Kaka, Boateng has responded fairly well to his new surroundings in Gelsenkirchen with four goals in 10 appearances across all competitions.

Yet with Schalke's visit to Stamford Bridge arguably their biggest game of the season so far, the German born Ghanian international has to produce the goods as one of his team's most experienced and best-paid stars.

The attacking midfielder's success abroad is often met with a sense of bemusement from Premier League viewers who remember him as a promising if precocious player for Tottenham Hotspur and Portsmouth.

Against Chelsea he has the ideal stage to showcase what English football is missing by leading the charge to dent Mourinho's hopes of topping Group E.

Having disappointed fans by missing a penalty and failing to change the direction of Schalke's 3-1 derby defeat against Borussia Dortmund, Boateng must also provide compensation for his sins in the Revierderby by being his team's key man at Stamford Bridge.

Samuel Eto'o and Adam Szalai

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Both Chelsea and Schalke are missing their primary forwards, with the injured Torres usually favoured by Mourinho in the Champions League and Huntelaar being the Germans' first-choice striker for every occasion.

That opens the floor to Eto'o and Szalai, who will be hoping to lead the line and score some pivotal goals for the home and away teams, respectively.

Considering his legendary reputation as one of the finest forwards of his generation, Eto'o has flattered to deceive for Chelsea, having so far only managed three goals from 15 appearances in all competitions.

His time in Russia with Anzhi may have blunted his predatory instincts, but with January looming the Cameroonian must start producing the goods in order to remain on the field.

Otherwise the bench could become his new position should a fresh face arrive to bolster the squad's attack in the new year.

Schalke miss Huntelaar.Shaun Botterill/Getty Images

Szalai has done well up front for Schalke but the Hungarian is far from prolific with five goals in 14 appearances.

That's better than Eto'o but it may not be enough to cause Chelsea's defence too much bother.

His team will need him to produce the highest level of performance he can in order to avenge their 3-0 home defeat last month.

Roman Neustadter

Neustadter in action for Germany.Joel Auerbach/Getty Images

Regardless of who lines up for Chelsea, the Blues will be able to field an exciting line of attacking midfielders able to play between the lines, score goals and pull defenders out of position.

That's why Neustadter is so important to Schalke's game plan in London, with the German defensive midfielder's tackling ability and defensive awareness vital for ensuring the Bundesliga team can hold their ground.

The 25-year-old will also want to make up for his less-than-assertive performance against Chelsea in Gelsenkirchen, especially considering his good form on domestic front of late.

His Champions League anomaly will hopefully enable Neustadter to focus his mind on frustrating and holding back the likes of Schurrle in order for Schalke to sneak a famous point or three back to Germany.

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Gary Cahill

With Mourinho once again unhappy with David Luiz, Cahill looks set to return to the Chelsea starting line-up alongside John Terry, who will need the former Bolton man to cover his fading pace at the back.

In some ways Cahill is a more orthodox version of the flamboyant Brazilian, with both centre-backs capable of scoring impressive long-range goals and offering a fair amount of mobility to ensure their lines are well guarded.

Although Schalke will be missing Huntelaar they are still a team bristling with attacking threats with Boateng, Julian Draxler and Max Meyer all capable of causing Chelsea problems if they aren't dealt with.

Like Schurrle, this is a big opportunity for Cahill to ensure that he becomes Mourinho's key man at the back.